Lung cancer is the uncontrolled growth of abnormal cells that start off in one or both lungs; usually in the cells that line the air passages. The abnormal cells do not develop into healthy lung tissue, they divide rapidly and form tumors. As tumors become larger and more numerous, they undermine the lung’s ability to provide the bloodstream with oxygen. Tumors that remain in one place and do not appear to spread are known as “benign tumors”.

Doctors viewing a lung x-ray for signs of lung cancer

Malignant tumors, the more dangerous ones, spread to other parts of the body either through the bloodstream or the lymphatic system. Metastasis refers to cancer spreading beyond its site of origin to other parts of the body. When cancer spreads it is much harder to treat successfully.

Primary lung cancer originates in the lungs, while secondary lung cancer starts somewhere else in the body, metastasizes, and reaches the lungs. They are considered different types of cancers and are not treated in the same way.

According to the National Cancer Institute, by the end of 2012 there will have been 226,160 new lung cancer diagnoses and 160,340 lung-cancer related deaths in the USA.

According to the World Health Organization (WHO), 7.6 million deaths globally each year are caused by cancer; cancer represents 13% of all global deaths. As seen below, lung cancer is by far the number one cancer killer.

Total deaths worldwide caused by cancer each year:

◾Lung cancer - 1,370,000 deaths

◾Stomach cancer - 736,000 deaths

◾Liver cancer - 695,000 deaths

◾Colorectal cancer - 608,000 deaths

◾Breast cancer - 458,000 deaths

◾Cervical cancer - 275,000 deaths

The American Cancer Society says that lung cancer makes up 14% of all newly diagnosed cancers in the USA today. It adds that annually, more patients die from lung cancer alone than prostate, breast and colon cancers combined (in the USA). An American man’s lifetime risk of developing lung cancer is 1 in 13; for a woman the risk is 1 in 16. These risk figures are for all US adults, including smokers, ex-smokers and non-smokers. The risk for a regular smoker is dramatically higher.

Most lung cancer patients are over the age of 60 years when they are diagnosed. Lung cancer takes several years to reach a level where symptoms are felt and the sufferer decides to seek medical help.

Female lung cancer rates set to rise rapidly

Over the next three decades, female lung cancers will increase thirty-five times faster than male lung cancers, scientists from King’s College London reported in October 2012.

In the UK, female lung cancer deaths will reach 95,000 annually in 2040, from 26,000 in 2010 – a rise of more than 350%. Male annual lung cancer deaths will increase by 8% over the same period, to 42,000 in 2040 from 39,000 in 2010.

The authors of the report say that lung cancer will continue being the largest cancer killer over the next thirty years. Twice as many people will be living with lung cancer in 2040 compared to 2010. The main reason for the increase will be longer lifespans - the older you are, the higher your risk of cancer is, including lung cancer.